4D Flow Cardiovascular Magnetic Resonance Research Articles

Inter-site comparability of 4D flow cardiovascular magnetic resonance measurements in healthy traveling volunteers—a multi-site and multi-magnetic field strength study

Inter-site comparability of 4D flow cardiovascular magnetic resonance measurements in healthy traveling volunteers—a multi-site and multi-magnetic field strength study

The value of blood flow velocity and pressure gradient in differentiating patients with different types of heart failure.

Patients with different types of heart failure (HF) exhibit varying rates of blood flow through cardiac chambers and pressure gradients across the aortic valve, attributed to differing degrees of myocardial contractility. Assessment of these dynamics offers insights into early HF diagnosis. This study aimed to analyze left ventricular outflow tract (LVOT) blood flow parameters, specifically peak blood flow velocity and pressure gradient derived from four-dimensional flow cardiovascular magnetic resonance (4D flow CMR), and to evaluate 4D flow CMR's utility in distinguishing HF types. This prospective cross-sectional study recruited 115 HF patients from January 2019 to May 2022 at the General Hospital of Ningxia Medical University, classified by the New York Heart Association Cardiac Function Classification of Heart Failure as class II-IV, alongside a control group (n=30). Participants underwent cardiovascular magnetic resonance (CMR), including 4D flow. HF patients were categorized into heart failure with reduced ejection fraction (HFrEF, n=55), heart failure with mildly reduced ejection fraction (HFmrEF, n=30), and heart failure with preserved ejection fraction (HFpEF, n=30), based on ejection fraction. The cardiac functional parameters and aortic valve flow indices were measured using Circle Cardiovascular Imaging. LVOT 4D flow data were obtained 3 mm below the junction of the aortic valve leaflets, assessing peak velocities above and below the valve. Differences in cardiac function and blood flow parameters between groups were analyzed using one-way analysis of variance (ANOVA). The accuracy of these parameters in identifying subgroups was assessed using the receiver operating characteristic (ROC) curve. Analysis of conventional cardiac function parameters revealed that left ventricular ejection fraction (LVEF) was significantly lower in the HFrEF and HFmrEF groups compared to the HFpEF and control groups (P<0.01). Additionally, end-diastolic volume and end-systolic volume were significantly higher in the HFrEF and HFmrEF groups than in the HFpEF and control groups (P<0.01). However, there were no significant differences in cardiac function parameters between the HFpEF and control groups (P>0.05). Significant differences were observed in aortic valve peak pressure gradients (Supra-APGmax) among the four study groups (5.01±1.09 vs. 6.23±2.94 vs. 7.63±1.81 vs. 8.89±2.97 mmHg, P<0.05). Aortic valve peak velocities in the HFrEF group differed significantly from the HFpEF and control groups (111.31±12.05 cm/s vs. 137.2±16 vs. 147.15±24.55 cm/s, P<0.001). The ROC curve for the pressure gradient below the aortic valve had an area under the curve (AUC) of 0.728 [95% confidence interval (CI): 0.591-0.864, P=0.002], with an optimal threshold of 4.72 mmHg (sensitivity: 0.8, specificity: 0.7, Youden index: 0.5). HF patients exhibit reduced pressure gradients across the aortic valve during systole, indicative of altered intracardiac blood flow dynamics. Combining aortic valve velocities and pressure gradients can aid in distinguishing different types of HF, including HFpEF patients.

Characteristics of altered biventricular hemodynamics after arterial switch operation for patients with d-transposition of the great arteries with preserved ejection fraction: a four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) study.

The long-term monitoring of biventricular function is essential to identify potential functional decline in patients following the arterial switch operation (ASO). The underlying pathophysiological mechanisms responsible for altered biventricular hemodynamics in ASO patients are not yet well understood. This study sought to: (I) compare the biventricular kinetic energy (KE) and vorticity of ASO patients and age- and sex-matched controls; (II) investigate the associations of four-dimensional (4D) flow biventricular hemodynamics parameters and neo-aortic root dilation, supravalvular pulmonary stenosis, and pulmonary artery transvalvular pressure difference. A total of 34 patients with dextro-transposition of the great arteries (D-TGA) who underwent ASO, and 17 age- and gender-matched healthy controls were prospectively recruited for this study. All the subjects underwent cine and 4D flow and late gadolinium enhancement scans, and all the patients underwent echocardiography within two weeks of cardiovascular magnetic resonance (CMR) imaging. The following four flow components were analyzed: direct flow, retained inflow, delayed ejection flow, and residual volume. In addition, the following six phasic blood flow KE parameters, normalized to the end-diastolic volume (EDV) and vorticity, were analyzed for both the left ventricle (LV) and right ventricle (RV): peak systolic phase, average systolic phase, peak diastolic phase, average diastolic phase, peak E-wave phase, and peak A-wave phase. The independent sample Student's t-test, Mann-Whitney U-test, univariable and multivariable stepwise regression analyses, intra and inter-observer variability analyses were used to compare patients and controls. In relation to the LV, the D-TGA patients had significantly decreased average vorticity, peak systolic vorticity, systolic vorticity, diastolic vorticity, and peak A-wave vorticity compared to the controls (all P<0.01). In relation to the RV, the pulmonary stenosis group had significantly increased peak E- and A-wave kinetic energy normalized to the end-diastolic volume (KEiEDV), and peak and average vorticity compared to the non-pulmonary stenosis group (all P<0.05). in the multivariable logistic regression model analysis, diastolic KEiEDV, peak E-wave KEiEDV peak A-wave KEiEDV, and average vorticity were associated a with transvalvular pressure difference (β=13.54, P<0.001 for diastolic KEiEDV; β=105.26, P<0.001 for peak E-wave KEiEDV; β=-49.36, P=0.027 for peak A-wave KEiEDV; and β=-56.37, P<0.001 for average vorticity). We found that 4D flow biventricular hemodynamics were more sensitive markers than the ejection fraction in the postoperative D-TGA patients. The RV diastolic KEiEDV parameters and average vorticity were risk factors for pulmonary artery obstruction in the multivariable model.

Assessment of abnormal transvalvular flow and wall shear stress direction for pediatric/young adults with bicuspid aortic valve: a cross-sectional 4D flow study

BackgroundAortic dilation is seen in pediatric/young adult patients with bicuspid aortic valve (BAV), and hemodynamic markers to predict aortic dilation are necessary for monitoring. Although promising hemodynamic metrics, such as abnormal wall shear stress (WSS) magnitude, have been proposed for adult BAV patients using 4D flow cardiovascular magnetic resonance, those for pediatric BAV patients have less frequently been reported, partly due to scarcity of data to define normal WSS range. To circumvent this challenge, this study aims to investigate if a recently proposed 4D flow-based hemodynamic measurement, abnormal flow directionality, is associated with aortic dilation in pediatric/young adult BAV patients. Methods4D flow scans for BAV patients (<20 years old) and age-matched controls were retrospectively enrolled. Static segmentation for the aorta and pulmonary arteries was obtained to quantify peak systolic hemodynamics and diameters in the proximal aorta. In addition to peak velocity, wall shear stress (WSS), vorticity, helicity, and viscous energy loss, direction of aortic velocity and WSS in BAV patients was compared with that of control atlas using registration technique; angle differences of >60deg and >120deg were defined as moderately and severely abnormal, respectively. Association between the obtained metrics and normalized diameters (Z-scores) were evaluated at the sinotubular junction, mid ascending aorta, and distal ascending aorta. ResultsFifty-three BAV patients, including eighteen with history of repaired aortic coarctation, and seventeen controls were enrolled. Correlation between moderately abnormal velocity/WSS direction and aortic Z-scores was moderate to strong at the sinotubular junction and mid ascending aorta (R=0.62-0.81; p<0.001) while conventional measurements exhibited weaker correlation (|R|=0.003-0.47, p=0.009-0.99) in all subdomains. Multivariable regression analysis found moderately abnormal velocity direction and existence of aortic regurgitation (only for isolated BAV group) were independently associated with mid ascending aortic Z-scores. ConclusionAbnormal velocity and WSS directionality in the proximal aorta was strongly associated with aortic Z-scores in pediatric/young adult BAV patients.

Clinical relevance of aortic conduit and reservoir function

BackgroundAortic conduit and reservoir functions can be directly measured by four-dimensional flow (4D flow) cardiovascular magnetic resonance (CMR).MethodsTwenty healthy controls (10 young and 10 age-gender-matched old controls) and 20 patients...

Direct comparison of whole heart quantifications between different retrospective and prospective gated 4D flow CMR acquisitions.

4D flow cardiovascular magnetic resonance (CMR) is a versatile technique to non-invasively assess cardiovascular hemodynamics. With developing technology, choice in sequences and acquisition parameters is expanding and it is important to assess if data acquired with these different variants can be directly compared, especially when combining datasets within research studies. For example, sequences may allow a choice in gating techniques or be limited to one method, yet there is not a direct comparison investigating how gating selection impacts quantifications of the great vessels, semilunar and atrioventricular valves and ventricles. Thus, this study investigated if quantifications across the heart from contemporary 4D flow sequences are comparable between two commonly used 4D flow sequences reliant on different ECG gating techniques. Forty participants (33 healthy controls, seven patients with coronary artery disease and abnormal diastolic function) were prospectively recruited into a single-centre observational study to undergo a 3T-CMR exam. Two acquisitions, a k-t GRAPPA 4D flow with prospective gating (4Dprosp) and a modern compressed sensing 4D flow with retrospective gating (4Dretro), were acquired in each participant. Images were analyzed for volumes, flow rates and velocities in the vessels and four valves, and for biventricular kinetic energy and flow components. Data was compared for group differences with paired t-tests and for agreement with Bland-Altman and intraclass correlation (ICC). Measurements primarily occurring during systole of the great vessels, semilunar valves and both left and right ventricles did not differ between acquisition types (p > 0.05 from t-test) and yielded good to excellent agreement (ICC: 0.75-0.99). Similar findings were observed for the majority of parameters dependent on early diastole. However, measurements occurring in late diastole or those reliant on the entire-cardiac cycle such as flow component volumes along with diastolic kinetic energy values were not similar between 4Dprosp and 4Dretro acquisitions resulting in poor agreement (ICC < 0.50). Direct comparison of measurements between two different 4D flow acquisitions reliant on different gating methods demonstrated systolic and early diastolic markers across the heart should be compatible when comparing these two 4D flow sequences. On the other hand, late diastolic and intraventricular parameters should be compared with caution.

Flow inefficiencies in non-obstructive HCM revealed by kinetic energy and hemodynamic forces on 4D-flow CMR.

Patients with non-obstructive hypertrophic cardiomyopathy (HCM) exhibit myocardial changes which may cause flow inefficiencies not detectable on echocardiogram. We investigated whether left ventricular (LV) kinetic energy (KE) and hemodynamic forces (HDF) on 4D-flow cardiovascular magnetic resonance (CMR) can provide more sensitive measures of flow in non-obstructive HCM. Ninety participants (70 with non-obstructive HCM and 20 healthy controls) underwent 4D-flow CMR. Patients were categorized as phenotype positive (P+) based on maximum wall thickness (MWT) ≥ 15 mm or ≥13 mm for familial HCM, or pre-hypertrophic sarcomeric variant carriers (P-). LV KE and HDF were computed from 4D-flow CMR. Stroke work was computed using a previously validated non-invasive method. P+ and P- patients and controls had comparable diastolic velocities and LV outflow gradients on echocardiography, LV ejection fraction, and stroke volume on CMR. P+ patients had greater stroke work than P- patients, higher systolic KE compared with controls (5.8 vs. 4.1 mJ, P = 0.0009), and higher late diastolic KE relative to P- patients and controls (2.6 vs. 1.4 vs. 1.9 mJ, P < 0.0001, respectively). MWT was associated with systolic KE (r = 0.5, P < 0.0001) and diastolic KE (r = 0.4, P = 0.005), which also correlated with stroke work. Systolic HDF ratio was increased in P+ patients compared with controls (1.0 vs. 0.8, P = 0.03) and correlated with MWT (r = 0.3, P = 0.004). Diastolic HDF was similar between groups. Sarcomeric variant status was not associated with KE or HDF. Despite normal flow velocities on echocardiography, patients with non-obstructive HCM exhibited greater stroke work, systolic KE and HDF ratio, and late diastolic KE relative to controls. 4D-flow CMR provides more sensitive measures of haemodynamic inefficiencies in HCM, holding promise for clinical trials of novel therapies and clinical surveillance of non-obstructive HCM.

Evaluation of left ventricular blood flow kinetic energy in patients with acute myocardial infarction by 4D Flow MRI: a preliminary study

PurposeTo evaluate the intracavity left ventricular (LV) blood flow kinetic energy (KE) parameters using four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) in patients with acute myocardial infarction (AMI).MethodsThirty AMI patients and twenty controls were examined via CMR, which included cine imaging, late gadolinium enhancement (LGE) and global heart 4D flow imaging. The KE parameters were indexed to LV end-diastolic volume (EDV) to obtain average, systolic and diastolic KE as well as the proportion of LV in-plane KE (%). These parameters were compared between the AMI patients and controls and between the two subgroups.ResultsAnalysis of the LV blood flow KE parameters at different levels of the LV cavity and in different segments of the same level showed that the basal level had the highest blood flow KE while the apical level had the lowest in the control group. There were no significant differences in diastolic KE, systolic in-plane KE and diastolic in-plane KE between the anterior wall and posterior wall (p > 0.05), only the systolic KE had a significant difference between them (p < 0.05). Compared with those in the control group, the average (10.7 ± 3.3 µJ/mL vs. 14.7 ± 3.6 µJ/mL, p < 0.001), systolic (14.6 ± 5.1 µJ/mL vs. 18.9 ± 3.9 µJ/mL, p = 0.003) and diastolic KE (7.9 ± 2.5 µJ/mL vs. 10.6 ± 3.8 µJ/mL, p = 0.018) were significantly lower in the AMI group. The average KE in the infarct segment was lower than that in the noninfarct segment in the AMI group (49.5 ± 18.7 µJ/mL vs. 126.3 ± 50.7 µJ/mL, p < 0.001), while the proportion of systolic in-plane KE increased significantly (61.8%±11.5 vs. 42.9%±14.4, p = 0.001).ConclusionThe 4D Flow MRI technique can be used to quantitatively evaluate LV regional hemodynamic parameters. There were differences in the KE parameters of LV blood flow at different levels and in different segments of the same level in healthy people. In AMI patients, the average KE of the infarct segment decreased, while the proportion of systolic in-plane KE significantly increased.

Volumetric Quantification of the Left Atrium by 4D Flow Cardiovascular Magnetic Resonance

Volumetric Quantification of the Left Atrium by 4D Flow Cardiovascular Magnetic Resonance

False lumen hemodynamics and partial thrombosis in chronic aortic dissection of the descending aorta.

Partial thrombosis of the false lumen (FL) in patients with chronic aortic dissection (AD) of the descending aorta has been associated with poor outcomes. Meanwhile, the fluid dynamic and biomechanical characteristics associated with partial thrombosis remain to be elucidated. This retrospective, single-center study tested the association between FL fluid dynamics and biomechanics and the presence and extent of FL thrombus. Patients with chronic non-thrombosed or partially thrombosed FLs in the descending aorta after an aortic dissection underwent computed tomography angiography, cardiovascular magnetic resonance (CMR) angiography, and a 4D flow CMR study. A comprehensive quantitative analysis was performed to test the association between FL thrombus presence and extent (percentage of FL with thrombus) and FL anatomy (diameter, entry tear location and size), fluid dynamics (inflow, rotational flow, wall shear stress, kinetic energy, and flow acceleration and stasis), and biomechanics (pulse wave velocity). Sixty-eight patients were included. In multivariate logistic regression FL kinetic energy (p = 0.038) discriminated the 33 patients with partial FL thrombosis from the 35 patients with no thrombosis. Similarly, in separated multivariate linear correlations kinetic energy (p = 0.006) and FL inflow (p = 0.002) were independently related to the extent of the thrombus. FL vortexes, flow acceleration and stasis, wall shear stress, and pulse wave velocity showed limited associations with thrombus presence and extent. In patients with chronic descending aorta dissection, false lumen kinetic energy is related to the presence and extent of false lumen thrombus. In patients with chronic aortic dissection of the descending aorta, false lumen hemodynamic parameters are closely linked with the presence and extent of false lumen thrombosis, and these non-invasive measures might be important in patient management. • Partial false lumen thrombosis has been associated with aortic growth in patients with chronic descending aortic dissection; therefore, the identification of prothrombotic flow conditions is desirable. • The presence of partial false lumen thrombosis as well as its extent was related with false lumen kinetic energy. • The assessment of false lumen hemodynamics may be important in the management of patients with chronic aortic dissection of the descending aorta.

The influence of post-processing software on quantitative results in 4D flow cardiovascular magnetic resonance examinations.

Several commercially available software packages exist for the analysis of three-dimensional cine phase-contrast cardiovascular magnetic resonance (CMR) with three-directional velocity encoding (four-dimensional (4D) flow CMR). Only sparse data are available on the impact of these different software solutions on quantitative results. We compared two different commercially available and widely used software packages and their impact on the forward flow volume (FFV), peak velocity (PV), and maximum wall shear stress (WSS) per plane. 4D flow CMR datasets acquired by 3 Tesla magnetic resonance imaging of 10 healthy volunteers, 13 aortic stenosis patients, and 7 aortic valve replacement patients were retrospectively analyzed for FFV, PV, and WSS using two software packages in six analysis planes along the thoracic aorta. Absolute (AD) and relative differences (RD), intraclass correlation coefficients (ICC), Bland-Altman analysis, and Spearman's correlation analysis were calculated. For the FFV and PV in healthy volunteers, there was good to excellent agreement between both software packages [FFV: ICC = 0.93-0.97, AD: 0.1 ± 5.4 ml (-2.3 ± 2.4 ml), RD: -0.3 ± 8% (-5.7 ± 6.0%); PV: ICC = 0.81-0.99, AD: -0.02 ± 0.02 ml (-0.1 ± 0.1 ml), RD: -1.6 ± 2.1% (-9.3 ± 6.1%)]. In patients, the FFV showed good to excellent agreement [ICC: 0.75-0.91, AD: -1.8 ± 6.5 ml (-8.3 ± 9.9 ml), RD: -2.2 ± 9.2% (-13.8 ± 17.4%)]. In the ascending aorta, PV showed only poor to moderate agreement in patients (plane 2 ICC: 0.33, plane 3 ICC: 0.72), whereas the rest of the thoracic aorta revealed good to excellent agreement [ICC: 0.95-0.98, AD: -0.03 ± 0.07 (-0.1 ± 0.1 m/s), RD: -3.5 ± 7.9% (-7.8 ± 9.9%)]. WSS analysis showed no to poor agreement between both software packages. Global correlation analyses revealed good to very good correlation between FFV and PV and only poor correlation for WSS. There was good to very good agreement for the FFV and PV except for the ascending aorta in patients when comparing PV and no agreement for WSS. Standardization is therefore necessary.

Kiosk 3R-TB-01 - Improved Quantitative Flow Analysis of Main and Branch Pulmonary Arteries Distal to the Vortex in Repaired Tetralogy of Fallot- a Single Center 4D Flow Cardiovascular Magnetic Resonance Study

Kiosk 3R-TB-01 - Improved Quantitative Flow Analysis of Main and Branch Pulmonary Arteries Distal to the Vortex in Repaired Tetralogy of Fallot- a Single Center 4D Flow Cardiovascular Magnetic Resonance Study

Hemodynamics and plasma biomarkers in individuals with mild-to-moderate ascending aortic dilatation and tricuspid aortic valves

Abstract Background Ascending aortic (AA) dilatation is a silent disease that requires frequent follow-up measurements of the AA diameter. Unfortunately, the AA diameter is an insufficient predictor of future growth and complications. Hemodynamic and circulating biomarkers represent promising ways of improving the risk stratification in AA dilatation. Most patients with AA dilatation have tricuspid aortic valves (TAV). However, previous studies have mainly focused on AA dilation in individuals with bicuspid aortic valves (BAV) using either hemodynamic or circulating biomarkers separately. Purpose To assess the relationship between hemodynamics in the AA and circulating biomarkers in individuals with mild-to-moderate AA dilatation and age-and-sex matched controls with TAV. Methods The study cohort of individuals with mild-to-moderate AA dilatation were identified based on AA diameter on coronary CT angiography in the population-based Swedish CardioPulmonary BioImage Study (SCAPIS) in Linköping. 54 cases with AA diameter &amp;gt;= 40 mm and 50 controls with AA diameter &amp;lt;40 mm (mean age 59, 19% female) underwent 4D Flow cardiovascular magnetic resonance imaging (CMR). The 4D Flow CMR images were processed to compute mean and maximum velocities, wall shear stress (WSS), flow displacement (FD) at peak systole, and oscillatory shear index (OSI) in the AA. Markers of collagen synthesis and degradation; type I collagen α1 chain (COL1α1), matrix metalloproteinase (MMP)-1,-2,-3,-9,-12) and their inhibitors (TIMP-1,-2,-3,-4), were quantified in plasma (n=104). High sensitivity C-reactive protein and interleukin(IL)-6 were used to assess systemic inflammation. Results FD at the location of maximum dilatation, mean FD and mean OSI were higher in cases compared to controls. Mean velocity, mean WSS and maximum WSS were lower in cases compared to controls. None of the circulating biomarkers differed significantly between cases and controls. Interestingly, several circulating biomarkers correlated with hemodynamics markers in the whole cohort. COL1α1, MMP-2 and TIMP-2 correlated inversely with max OSI (r=-0.342, p=0.001; r=-0.277, p=0.006; r=-0.238, p=0.018, respectively) while MMP-3 correlated positively with mean velocity (r=0.274, p=0.006), mean WSS (r=0.270, p=0.007), max WSS (r=0.220, p=0.029), and inversely with FD at the location of maximum dilatation (r=-0.218, p=0.031). TIMP-4 correlated with mean OSI (r=-0.284, p=0.005). Conclusions Several hemodynamic markers obtained with 4D Flow CMR were altered in mild-to-moderate AA dilatation with TAV, while circulating biomarkers did not differ from controls. However, significant correlations were identified between several biomarkers and hemodynamic markers. We therefore speculate that the levels of circulating biomarkers may be altered as the disease progresses. Future studies should examine the implications of these novel findings along the trajectory of AA dilation and its association with complication risk.Methods figureHemodynamics markers table

Abstract 14833: Association of RV Hemodynamics From 4D Flow CMR With RV Restrictive Physiology From Pediatric to Adult Repaired Tetralogy of Fallot

Introduction: Right ventricular restrictive physiology (RVRP) is common after repair of Tetralogy of Fallot (rTOF), especially with residual pulmonary regurgitation. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) quantitates biventricular blood flow components and kinetic energy (KE) parameters, but their association with RVRP is unclear. We aimed to study 4D flow CMR parameters in adult and pediatric rTOF patients vs healthy controls and associations of 4D flow parameters with RVRP in rTOF. Methods: 103 rTOF patients (40 pediatric, 63 adult; age 24±17 years; 53M:50F) and 171 healthy controls (14 pediatric, 157 adult; age 40±15 years; 97M:74F) were prospectively recruited from centers in Singapore (2) and China (1) to undergo 4D flow CMR on multi-vendor scanners. LV and RV flow components—direct flow, retained inflow, delayed ejection flow and residual volume—and KE parameters (normalized to end-diastolic volume, KEi EDV )—global, peak systolic, average systolic, average diastolic, peak E-wave and peak A-wave—were analyzed. KE discordance was calculated as the ratio of RV and LV average systolic KEi EDV . Results: See Table. RVRP was identified in 70 patients (68%). rTOF with RVRP exhibited higher median RV stroke volume index, RV ejection fraction, RV direct flow, RV peak E-wave and E-wave/A-wave, and lower RV residual volume compared to rTOF without RVRP (all P&lt;0.05). Using binary multivariable logistic regression analysis—and after adjustment for age, pulmonary regurtitation, LV and RV ejection fraction, RV direct flow was found to be independently associated with RVRP in rTOF (P&lt;0.001). Conclusion: Patients with RVRP had higher RV direct flow, RVEF and RV peak E-wave energy, indicating the potential compensatory adaptations in patients with RVRP.

Abstract 16562: Subclinical Flow Inefficiencies in Non-Obstructive Hypertrophic Cardiomyopathy Subgroups Revealed by 4D Flow Cardiovascular Magnetic Resonance

Background Patients with non-obstructive hypertrophic cardiomyopathy (nHCM) may exhibit flow inefficiencies despite normal flow profiles on transthoracic echocardiogram. We investigated whether left ventricular (LV) kinetic energy (KE) and hemodynamic forces (HDF) on 4D flow CMR are abnormal in nHCM, and examined the impact of genotype and hypertrophy phenotype on flow profiles. Methods 90 participants (70 HCM without echocardiographic outflow tract obstruction and 20 healthy controls) underwent 4D flow CMR. Patients were categorized as phenotype positive (P+) if they had LV hypertrophy (≥15mm or ≥13mm with an HCM family history), or phenotype negative (P-) referring to pre-hypertrophic pathogenic sarcomeric variant carriers. LV KE, HDF and transversal/longitudinal HDF ratio were computed from 4D flow CMR. Results P+ patients and controls were of similar age, but P- were younger. P+, P- and controls had comparable LV ejection fraction on CMR, and LV outflow tract pressure gradients and diastolic velocities on echocardiography (Table 1). Systolic KE was higher in P+ compared to controls (Table 1, Figure 1). Early diastolic KE was higher in P- than P+, reflecting younger P-, but did not differ between P+ and controls. Late diastolic KE was higher in P+ versus P- and controls. Systolic HDF ratio was higher in P+ than controls (Table 1, Figure 1). Diastolic HDF and HDF ratio were similar between P+ and controls. Conclusion Despite comparable flow velocities on echocardiography, nHCM exhibited higher systolic KE and HDF ratio, and late diastolic KE on 4D flow CMR relative to controls. Both the extent and pattern of hypertrophy are important determinants of abnormalities in KE and HDF.

Oscillatory shear stress is elevated in patients with bicuspid aortic valve and aortic regurgitation: a 4D flow cardiovascular magnetic resonance cross-sectional study.

Patients with bicuspid aortic valve (BAV) and aortic regurgitation have higher rate of aortic complications compared with patients with BAV and stenosis, as well as BAV without valvular disease. Aortic regurgitation alters blood haemodynamics not only in systole but also during diastole. We therefore sought to investigate wall shear stress (WSS) during the whole cardiac cycle in BAV with aortic regurgitation. Fifty-seven subjects that underwent 4D flow cardiovascular magnetic resonance imaging were included: 13 patients with BAVs without valve disease, 14 BAVs with aortic regurgitation, 15 BAVs with aortic stenosis, and 22 normal controls with tricuspid aortic valve. Peak and time averaged WSS in systole and diastole and the oscillatory shear index (OSI) in the ascending aorta were computed. Student's t-tests were used to compare values between the four groups where the data were normally distributed, and the non-parametric Wilcoxon rank sum tests were used otherwise. BAVs with regurgitation had similar peak and time averaged WSS compared with the patients with BAV without valve disease and with stenosis, and no regions of elevated WSS were found. BAV with aortic regurgitation had twice as high OSI as the other groups (P ≤ 0.001), and mainly in the outer mid-to-distal ascending aorta. OSI uniquely characterizes altered WSS patterns in BAVs with aortic regurgitation, and thus could be a haemodynamic marker specific for this specific group that is at higher risk of aortic complications. Future longitudinal studies are needed to verify this hypothesis.

4D-Flow Cardiovascular Magnetic Resonance Versus 3D Transesophageal Echocardiography in Multifenestrated Atrial Septal Defect.

4D-Flow Cardiovascular Magnetic Resonance Versus 3D Transesophageal Echocardiography in Multifenestrated Atrial Septal Defect.

Quantifying 4D flow cardiovascular magnetic resonance vortices in patients with pulmonary hypertension: A pilot study.

In this 4D flow cardiovascular magnetic resonance (CMR) study, vortical blood flow in the main pulmonary artery (MPA) is quantified using circulation (ᴦ), a metric used in fluid dynamics to quantify the rotational components of flow. Circulation (ᴦ) is a 4D flow CMR metric that quantifies the vortical blood flow pattern in the MPA of patients with pulmonary hypertension (PH), distinguishes them from healthy controls, and shows high correlation with invasive markers of PH severity.

Intraventricular 4D flow cardiovascular magnetic resonance for assessing patients with heart failure with preserved ejection fraction: a pilot study.

Diagnosing heart failure with preserved ejection fraction (HFpEF) remains challenging. Intraventricular four-dimensional flow (4D flow) phase-contrast cardiovascular magnetic resonance (CMR) can assess different components of left ventricular (LV) flow including direct flow, delayed ejection, retained inflow and residual volume. This could be utilised to identify HFpEF. This study investigated if intraventricular 4D flow CMR could differentiate HFpEF patients from non-HFpEF and asymptomatic controls. Suspected HFpEF patients and asymptomatic controls were recruited prospectively. HFpEF patients were confirmed using European Society of Cardiology (ESC) 2021 expert recommendations. Non-HFpEF patients were diagnosed if suspected HFpEF patients did not fulfil ESC 2021 criteria. LV direct flow, delayed ejection, retained inflow and residual volume were obtained from 4D flow CMR images. Receiver operating characteristic (ROC) curves were plotted. 63 subjects (25 HFpEF patients, 22 non-HFpEF patients and 16 asymptomatic controls) were included in this study. 46% were male, mean age 69.8 ± 9.1years. CMR 4D flow derived LV direct flow and residual volume could differentiate HFpEF vs combined group of non-HFpEF and asymptomatic controls (p < 0.001 for both) as well as HFpEF vs non-HFpEF patients (p = 0.021 and p = 0.005, respectively). Among the 4 parameters, direct flow had the largest area under curve (AUC) of 0.781 when comparing HFpEF vs combined group of non-HFpEF and asymptomatic controls, while residual volume had the largest AUC of 0.740 when comparing HFpEF and non-HFpEF patients. CMR 4D flow derived LV direct flow and residual volume show promise in differentiating HFpEF patients from non-HFpEF patients.

Fluid dynamics by 4D flow CMR in Marfan and Loeys-Dietz patients before and after valve sparing aortic root replacement

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III (Spain), Sociedad Española de Cardiología Introduction Patients with Marfan or Loeys-Dietz syndrome present abnormal aortic flow patterns in the arch and the proximal descending aorta that may contribute to aortic dilation (1,2). Valve sparing aortic root replacement, which is effective in reducing the risk of aortic dissection in case of severe dilation, may also normalize flow patterns beyond the replaced aorta and potentially slow its progressive aortic dilation. Purpose To assess aortic flow dynamics in these patients with Marfan or Loeys-Dietz by 4D flow cardiovascular magnetic resonance (CMR) before and after valve sparing aortic root replacement (David surgery), and to compare the results with those of healthy volunteers (HV). Methods Patients with Marfan or Loeys-Dietz syndrome underwent two non-contrast enhanced 4D flow CMR, one before and another after undergoing David surgery. Healthy volunteers matched for age, sex and BSA were also included for comparison. Maximum velocity, in-plane rotational flow (IRF), systolic flow reversal ratio (SFRR) and wall shear stress (WSS) magnitude and its axial and circumferential components were obtained at 24 planes covering the thoracic aorta from the sinotubular junction to the descending aorta at the diaphragmatic level (3–5). Results Sixteen patients and 21 healthy volunteers were included. Demographic and clinical data is presented in Table. The mean time between the CMR prior and posterior to surgery was 15 months. Compared to HV, patients with CTD before intervention presented lower maximum velocity at the proximal ascending aorta (Figure 1A), lower IRF and circumferential WSS at the arch and the proximal descending aorta (Figure 1B and F), lower magnitude and axial WSS at the proximal ascending and descending aorta (Figure 1E and D), and increased SFRR at the proximal descending aorta (Figure 1C). The intervention completely restored maximum velocity and partially-restored physiological helical flow and circumferential WSS, but barely improved axial WSS and SFRR. Conclusion Valve sparing aortic root replacement in patients with Marfan or Loeys-Dietz syndrome partially restore to physiological level both in-plane rotational flow and circumferential wall shear stress in the descending aorta.